For a number of years the commercial process of making blowing wool insulation has included the use of a hammermill wherein rotating hammers in a casing break up masses of fibrous glass wool and force it through a plate having a plurality of orifices to form it into irregularly shaped nodules.
In one process of making blowing wool, masses of fibrous glass wool are picked apart and the fibers are reformed into an even mat which is sprayed with water and slit and chopped into cubes. The cubes are advanced through troughs in which they are paddled by a series of rotating beater blades and rolled into nodules.
In a more recent development, columns of fibrous glass blowing wool are produced and bagged without any beating or padding into nodules. The columns break up at random, during the bagging process and when blown into place for insulation, into smaller prisms, approximating cubes, or flakes of various thicknesses.
The use of fiber glass blowing wool or loose-fill insulation is well known and is preferred by many contractors because it can be easily and quickly applied to new and old buildings and is a relatively low cost material. The loose fill insulation can be pneumatically applied over large horizontal surfaces. Often, the distribution of the blowing wool through the application nozzle and air creates a static charge on the fiber surfaces. These electric charges repel each other causing small fiber particles to spread out causing a "cloud of dust".